(a) Where initial application for parole has been denied, a prisoner's case may be subse- quently reviewed by the board. A request for a review will be granted when the chairman deter- mines that such review is justified on the basis of receipt of sufficiently significant information which was not known to the board at the time of any previous consideration.

(b) In the absence of such significant information, the board may call for review at any time when they determine such review is merited by the circumstances. In all cases, the board must review decisions at least once each year after a denial.